During surgical operations and other invasive procedures, it is conventional to cover a patient and nearby equipment with sterile drapes to prevent microorganisms and other foreign matter from invading the patient and to keep equipment clean. It has been known in the past to construct surgical drapes with cheap, easily disposable material, such as cellulosic material or plastic film. Such surgical drapes are sometimes provided with precut fenestrations to provide access to a patient with surgical tools and the like and are also sometimes provided with straps to fasten the drape to the patient or equipment.
It has also been known to construct entire surgical drapes with a transparent material to aid in viewing the patient. Such construction is shown in the patent to Jessamine et al., U.S. Pat. No. 4,903,710, which provides a surgical drape comprising a sheet of flexible transparent or translucent plastic material. It has also been known to provide a viewing window made of transparent plastic in the center of a non-transparent surgical drape. Such a viewing window is shown in the patent to Hadtke et al., U.S. Pat. No. 3,721,234, which discloses a surgical drape composed of cellulosic material with an enlarged opening and having a clear plastic sheet covering the opening.
Surgical operations and other medical procedures are often performed under an x-ray machine, which includes an x-ray emitter and an image intensifier (collector) fluoroscopy tube. Although prolonged exposure to x-rays is dangerous, medical procedures were often performed in years past using an x-ray machine that has remained on for extensive periods during the procedure so that doctors and other medical personnel could see what they were doing. Upon the advent of laser targeting devices, which aim a laser beam in the path of the x-ray beam, surgery and other operative procedures could be performed without extensive x-ray exposure. The laser beam provides a visible target that aids a doctor in maintaining an accurate reference axis without extensive operation of the x-ray machine, thereby reducing radiation exposure to doctors and patients. An example of a laser targeting device is disclosed in the inventors' co-pending U.S. patent application, Ser. No. 08/344,467, filed Nov. 23, 1994, which is hereby incorporated by reference.
One problem that has arisen with the use of laser targeting devices in surgical procedures relates to the use of a surgical drape to protect the laser targeting device and x-ray machine from blood and other contaminants inherent in surgical operations and also to prevent any microorganisms from the laser targeting device infecting the patient. Currently, laser targeting devices are generally covered with drapes made of polyethylene or other inexpensive plastic that work well to keep the devices clean, but do not permit good transmission of the laser beam through the drape. This is because drapes currently used to cover laser targeting devices are not entirely clear or are easily wrinkled and, therefore, cause diffusion and diffraction of the laser light. Another problem with previously used drapes is that such drapes are not sized and shaped specifically to cover an end of a C-arm-type x-ray machine having a laser targeting device mounted thereon. When an ordinary drape is pulled over the end of the C-arm, it generally becomes wrinkled and distorted, which enhances the aforementioned laser beam transmission problems.